Apparatus for pulverizing



Jan.,l, 1929. 1,997,794

V W. R. WOOD APPARATUS FOR PULVERIZING Filed Feb. 24, 1927 4 7mm? ya a cles return to the disc aforesaid.

Patented Jan. 1, 1929.

mama,

WILFRED ROTHERY WOOD, OF LONDON, ENGLAND, ASSIGNOR TO INTERNATIONAL COMBUSTION ENGINEERING CORPORATION, OF NEW YORK, N. Y.. A CORPORATION OF DELAWARE.

APPARATUS FOR PULVERIZING.

Application filed February 24, 1927, serial No. 170,441, and in Great Britain April 1, 1926.

ing cross'section in upward direction. The

particles of the material travel on the disc under centrifugal force, suffering attrition. "When they leave the periphery of the disc they are returned to the space above the'disc partly by reflection from the inner surface of the casing, or from ribs or plates which this surface may carry, and partly by deflection by an air current set up in the casing by the revolving disc. Falling again upon the.

disc the particles again travel on the latter under centrifugal force, suffering further attrition and are again returned as before to the disc.

In order to separate the sufficiently finely ground particles from those that are coarser,

air may be admitted to the casing and a vent therefor provided. The current of "air through the casing' thuscreated, and if desired enhanced by forming the under surface of the disc with blades or the like so that the disc may act as a fan, carries the fine particles through the vent, while the coarse parti- This effect may largely be due to the swirling motion of the current caused by the revolving disc, since the coarse, heavier particles are prevented by centrifugal force from escaping through the vent when this is axial.

Since the pulverizing action is mainly due to attrition, it is useful to provide an abrasive surface to the disc and the inner surface of the casing may also be of a particularly abrasive nature.

For the same reason it is advantageous that the disc should be dished or of bowl-shape, since this formation increases the pressure of the particles against the surface of the disc as they move under centrifugal force.

The invention is particularly applicable to the pulvcrizing of coal.

The accompanying drawing is an axial section through a'mill constructed in accordance with the invention.

The circular dish a is mounted within the casing b to rotate-at high speed together with the shaft ,0. The greater part of the surface of the dish consists of an abrasive material (2, such as carborundum.

The upper part of the casing b curves inwards towards the centre of the disc, shown, and is cast with an internal dished ring 7', which is preferably hollow for the sake of lightness. The under surface of this ring has substantially the same curvature as that of the upper surface of dish a and the two surfaces are fairly close together.

The dish a is cast with blades 9 which operate as the blades of a fan in the conical lower portion of the casing 12. a

The aXiaLpipe h serves for passage of air leaving the mill and carrying the finely subdivided product. The material to be ground fed from a hopper i by any well-known feeding device 70. 1t passes down a chute e co-axial with pipe 0, and is distributed by the cone Z on to the dish a which is revolved at a very high speed.

The particles of material are compelled-by centrifugal action to travel up the curved surface of dish a under a pressure far exceeding that represented by their weight, so that they are reduced insize by ZLttIltliOlll against the grinding material (Z. At the pe riphery of the disc they enter a rapid current of air induced by the blades 9. Those particles which are not sufficiently fine to be dlverted at once by this air current and carried as indicated by arrow'm into the space immediately below the pipe h, strike the internal surface of the casing b and are reflected into the said space, Where they fall back on to the plate a to be further'treated. The fines are carried by the air current through the pipe k, to be disposed of in known manner. 1

The air induced by the fan blades 9 may be preheated, if desired; but even with air at ordinary temperature, the drying effect is good, because local currents of air, as indicated by arrows n, are set up in the mill.

Having thus described the nature of the said invention and the best means I know of ciirrying the same into practical effect, I c a1m:-

1. An attrition pulverizing mill compris ing a casing, a disc within the casing having "an attrition surface, means whereby said disc 2 .may be revolved at high speed, means for f feeding material to be pulverized to the center of the disc, the inner surface of the portion of the casing above the disc inclining inwardly and then downwardly to a-central exitopening, and means for creating a' ourrent o'fairupwardly pastthe periphery of the disc.

-2, "An attrition pulverizing mill comprising a casing, a disc Within the casing having an attrition surface, means whereby said disc may revolved at high speed, means for feedin ,material to be pulverized to thcenter'oft e disc, the inner surface of the portion of the casing above the disc inclining in- 'wardly and then downwardly to a central exit opening, and means for creating a cursplrally moving current of air flowing up- 'wardlpast the periphery of the disc.

n attrition pulverizing mill comprising a casing,-a disc withinthe casing having yanattrition surface, means whereby said disc" .may be revolved at high speed, means for feeding material to be pulverized to-the center of the disc, the inner surface of the-por tion'of' the casing above thedisc inclining inwardlyand then downwardly to a central 1 exit opening, the central portion of said cas ing aboveothe disc being unobstructed,'and

means for creating a spirally moving current of air flowing upw y P the periphery Of-the disc? v v v 4.; An attrition pulverizing mill comprising a casing, a disc within the casing having an attrition surface, means whereby said disc may be revolved 'at high speed, means for tion of said casing'being unobstructed, and

:feeding material to'be pulverized to the cen ter-of the disc, the inner surface of the portion of the casing above the disc inclining inwardly and then downwardly to a. central exit opening, the downwardly inclined pormeans for creating a spirally moving current of air flowing upwardly past-the periphery .of the disc. v p I -5 An attrition pulverizing millcomprising a casing, a-disc within the casing having an attrition surface, means whereby said disc .maybe revolved at high speed, means for.

feeding 'material to be pulverized to the cen'- ter ofthe disc, the inner surface of the por-' tion of the casing above the said disc inclining v upwardly and then inwardly to a central exit opening which is lower than ''the highest;

upwardly having an unobstructed attrition surface, 'means whereby said disc may be revolved at a high speed, a chute above the center of thedisc for discharging-material to be pulverized onto the disc, an outlet pipe surrounding said chute, the diameter of theloutlet pipe Y beingsubstantially less than the diameter of the disc, and-means for creating a current of air upwardly past the periphery of the disc. 7 i A pulverizing mill-comprising a casing, a dished disc'wi-thi'n the casing and of a slightly smaller diameter than the widest portion of the said casing, a substantially verticalshaft on which the said disc is mount-,

ed and which is adaptedto rotate at high speed, the part of the said casing which is above the disc being curved inwardly towards. a

the center of the ,disc,a dished'ring mounted within the casing so as ,to haveits inner surface nearto theup er surface of the said disc,

an abrasive materlal forming a part of the upper surface of the said disc, fan blades car-4 ried b the under surface of the said disc, an inlet for air to the'casin below the disc, an

axially arranged outlet or air on the casing abovethe disc, a-"feed pipe co-a'xial with the saidoutlet and means for feeding the material to be pulverized on to'the disc through the said feed pipe.

8. An attrition pulverizing mill comprisinga casing, a-dished-disc within the casing said disc may be revolved athign fspeed, meansfor feeding material to, be pulverized of the exit entrance being substantially proximate :to the; horizontal plane ofthe upper edge of theldishe'd disc, and means for creating a current ofairupwardly past the. peripher of the disc.

11. testimony whereof name to this specification.

- .WI'LFREDIROTHERY WOO-D..-

having an attrition surfa'ce, means whereby tothe surface ofthe disc, the casing having-a central exit opening above-the disc, the plane I have signed GERTEHCATE 0F QURRIECTWN.

Patent No. 1,697,704. I Graintoti January 1, i929, to

. wtrrmzo norrirnrwooo.

it is hereby certified that error appears in the printed specification oi tho I above numbered patent requiring correction as follows: Page 2, line 20., claim 2; strike out the'syiiabic 'cnr-"; and that thc'said Letters Patent should he read! with this correction therein that tho same may coniorrn. to the rccord oi the case in tho Patent Office. I

Signed anti seaicd this 5th day of February, A., D. 1929.

. ii. Moore (Scai) Acting Commissioner oi Patentsv 

